Packaging with heat-shrinkable film

ABSTRACT

A stack of articles is packaged in a bag or sheet of heatshrinkable film. Film at the bottom of the stack is not heat shrunk so that individual articles can be removed without destroying the package.

United States Patent Fritz et a1.

[ 1 Feb. 8, 1972 [54] PACKAGING WITH HEAT- SHRINKABLE FILM [72] Inventors: Richard C. Fritz; Aldo B. Galvanoni, both of Cincinnati, Ohio [73] Assignee: Phillips Petroleum Company [22] Filed: Jan. 29, 1969 [21] App1.No.: 795,097

[52] U.S. Cl ..53/30, 34/216, 53/184 [51] Int. Cl ..B65b 53/06 [58] Field ofSearch ..53/30, 184, 182,212; 39/216 [56] References Cited UNITED STATES PATENTS 3,087,610 4/1963 Kirkpatrick .....s3/s0ux A 3,187,478 6/1965 Kirkpatrick ..53/30 3,555,772 [[1971 Kammer ..53/184 X FOREIGN PATENTS OR APPLICATIONS 1,062,370 3/1967 Great Britain "53/30 Primary Examiner-Travis S. McGehee Assistant ExaminerEugene F. Desmond Attorney-Young and Quigg 57 ABSTRACT A stack of articles is packaged in a bag or sheet of heatshrinkable film. Film at the bottom of the stack is not heat shrunk so that individual articles can be removed without destroying the package.

1 Claims, 2 Drawing Figures PATENTED rza 8:912 3,640,049

HEATER COOLANT INVENTOR. RC. FRITZ A.B.GALVANON| A TTOR/VEYS PACKAGING WITH I-IEAT-SIIRINKABLE FILM Heat-shrinkable film is used extensively in packaging various types of merchandise. This procedure is particularly useful when a number of articles are to be packaged in a single container. In operations of this type, the articles are placed in a bag or wrapped in thennoplastic film which is heat shrinkable. The resulting package is then subjected to an elevated temperature to shrink the film around the articles. When a package of this type is opened by the consumer, the protective film is normally destroyed. While this is usually not objectionable, a problem arises when a plurality of items are packaged together and the consumer desires to use only one item at a time. If the protective film is destroyed-when the package is opened, it may be necessary to find a new container for the unused items.

In accordance with the present invention, an improved method is provided for packaging a plurality of items in heatshrinkable film. This is accomplished by retaining a portion of the film at a relatively low temperature during the heating step so that this portion of the film is not shrunk to any appreciable extent. Single articles can then be removed individually while the remaining articles are retained together by the shrunk portion of the film. This procedure is particularly effective in packaging a plurality of articles of generally annular shape,

such as rolls of tape, for example. The rolls can be positioned in a loose-fitting bag of heat-shrinkable material and the ends of the bag tucked into the hollow central openings of the rolls. The resulting package can readily be opened by withdrawing the tucked ends, which are not heat shrunk.

Accordingly, it is an object of this invention to provide an improved method of packaging multiple articles in heatshrinkable film. Another object is to provide novel packages constructed of heat-shrinkable film. A further object is to provide apparatus for use in heat-shrunk packaging.

In the drawing, 2

FIG. 1 illustrates the packaging of a plurality of rolls in a bag of heat-shrinkable film.

FIG. 2 is a schematic illustration of apparatus employed to heat shrink the film on the rolls.

Referring now to the drawing in detail and to FIG. 1 in particular, there is shown a stack of hollow articles 10, such as rolls of tape. A bag 11 of heat-shrinkable film is placed over the stack of tape rolls and the lower open end of the bag is tucked into the hollow core of the stack. Although it is desirable to use a bag for this purpose, the stack of rolls can be wrapped in a sheet of film with the edges tucked into the hollow core.

The film employed to form bag 11 can be any conventional heat-shrinkable thermoplastic film. Various materials are well known in the art for this purpose. These include polyethylene, polypropylene, poly(vinyl)chloride, polystyrene and polyester. These heat-shrinkable films are manufactured by a process which results in the film being stretched while it is being formed. The subsequent application of heat tends to shrink the film. Heat-shrinkable films of thermoplastic materials of the types mentioned are available commercially and have a typical gauge in the range of about one-fourth to 5 mils.

After the stack of rolls has been placed in bag 11 as illustrated in FIG. 1, heat is applied to the sides and top of the resulting package to shrink the film into a tight fit with the rolls. However, the bottom portion is retained at a relatively low temperature so that little if any shrinkage takes place. This permits the end of the bag to be withdrawn from the central core when it is desired to withdraw one or more rolls from the package. After such withdrawal, the end of the bag can once again be tucked into the central core to close the package.

Apparatus which can be employed to advantage to carry out the heating step of this invention is illustrated schematically in FIG. 2. A conveyor belt 12, which is driven by a source of power not shown, is positioned so as to extend through a housing 13. The packages of FIG. 1 are placed on conveyor 12 so as to be moved through housing 13 by the conveyor. It is important that thesepackages be retained in an upright position so that the bottom of theipackage is not exposed directly to heated air within the housing. This can be accomplished by attaching a plurality of guide pins 14 to the conveyor. A blower 16 is secured to housing 13 to deliver a stream of air at an elevated temperature from a heater 15 into the housing to contact the packages. This air is supplied at a temperature which is suitable to shrink the particular film being employed. Temperatures in the general range of to 450 F. are usually employed for this purpose. The particular temperature selected depends to a large extent on the melting point of the packaging film. The temperature of the air and the residence time of the package in housing 13 are selected for any particular film so that the film is shrunk to a tight fit on the stack of rolls.

As previously mentioned, it is important to maintain the bottom of the package at a relatively low temperature so that no appreciable shrinking of the film takes place in this region. The physical placing of the stack of rolls in an upright position on conveyor 12 is adequate in some operations to maintain the bottom of the stack at the desired low temperature. In other operations, it is desirable to cool the lower end of the package. This can be accomplished by placing a cooling coil 17 within housing 13 immediately below the surface of conveyor 12. Any suitable coolant can be passed through coil 17 from a refrigerant source 18. As an alternative, coil 17 can be placed below conveyor 12 outside housing 13 to cool the convcyor and the stack of articles before entry into the housing.

The package resulting from the heat shrinking step carried out by the apparatus of FIG. 2 can be opened without destroying the film because the end tucked in at the bottom is not shrunk to any appreciable extent. This permits one or more rolls to be removed and the package closed by once again tucking in the end of the bag. It should be evident that the procedure of this invention is particularly useful in packaging a plurality of articles of generally annular or similar configuration. In addition to rolls of tape, other items which can advantageously be packaged include nested articles such as glasses and cups, spools of thread, cord and the like, and food products such as doughnuts. When the articles have a hollow central core, the ends of the film or bag can be tucked into the core for sealing purposes. If the articles are not hollow, the bottom can be sealed after the heat shrinking step by the use of adhesives or other fastening means to secure the ends of the film together. In some applications, both ends of the stack can be retained at a low temperature to provide a package that can be opened from either end.

In some operations, the material to be packaged can be placed on a disk of insulating material 20, as shown in FIG. I. This disk keeps the end of the package relatively cool during passage through housing 13.

While this invention has been described in conjunction with presently preferred embodiments, it should be evident that it is not limited thereto.

We claim:

1. The method of packaging a stack of articles which comprises wrapping the stack of articles in a sheet of heat-shrinkable film, placing the wrapped stack on a movable belt so that the stack rests on one end of the stack, moving the belt with the stack thereon through a heating zone, cooling the belt as it is passed through the heating zone to assist in preventing the film on said end of the stack from being shrunk, and passing a stream of hot air into the heating zone to strike the wrapped stack as the belt moves the stack through the heating zone, whereby the film is shrunk except at said end which rests on the belt so as to be out of contact with the stream of hot air, thereby producing a package which can be opened at said end to permit removal of articles. 

1. The method of packaging a stack of articles which comprises wrapping the stack of articles in a sheet of heat-shrinkable film, placing the wrapped stack on a movable belt so that the stack rests on one end of the stack, moving the belt with the stack thereon through a heating zone, cooling the belt as it is passed through the heating zone to assist in preventing the film on said end of the stack from being shrunk, and passing a stream of hot air into the heating zone to strike the wrapped stack as the belt moves the stack through the heating zone, whereby the film is shrunk except at said end which rests on the belt so as to be out of contact with the stream of hot air, thereby producing a package which can be opened at said end to permit removal of articles. 